Ed Asner Hospitalized -- Medical Emergency During Live Performance

Ed Asner was rushed to a hospital near Gary, Indiana yesterday ... after the 83-year-old actor suffered a medical emergency during a performance of his 1-man show.

15 minutes into his play "FDR" -- crew members escorted Asner off the stage after noticing the actor struggling with his lines.

According to SunTimes.com, Asner was taken by ambulance to a nearby hospital for treatment.

Asner is a Hollywood legend -- having won Emmys for his role on "The Mary Tyler Moore Show" and the spin-off "Lou Grant."

He was also the president of the Screen Actors Guild.

8:45 AM PT -- TMZ spoke with Ed's son, Matt, who tells us ... "My dad is doing fine. He was rushed to the hospital yesterday for being disoriented on stage."

"He is resting now at an Indiana hospital and is doing well and very grumpy, which with him is always a good thing."

"He is being assessed right now and what I can say is that it was not a stroke. That much we do know."

"He was feeling under the weather for a few weeks so he may just need some rest but for now he is just fine."